1. Field of the Invention
The invention concerns a line deadend structure and method for securing transmission or distribution lines at a termination point. More specifically, the invention is directed to a substation deadend structure that includes a single pole which is connected to three-phase high voltage lines and which drops the lines to an electrical mechanism located at ground level. Although directed toward utility systems, this invention is applicable to both utility and non-utility installations.
2. Discussion of the Related Art
Very high voltage is routinely transmitted over 3 transmission wires which, in North America, are referred to as A-phase voltage, B-phase voltage, and C-phase voltage wires. In other areas of the world, transmission wires are sometimes referred to differently, such as R, S and T phase wires in Europe. Once voltage that is carried over the transmission lines reaches an area, such as a town, city, subdivision, large industrial facility, etc., in which the power will be used, voltage is stepped down at a substation to a working level.
Typically, large metal or concrete frame dead end structures have been used to anchor or terminate the ends of the transmission lines at the substations. The large frame structures are necessary to counter the high tension forces present in the transmission lines. The dead end structure permits the transmission lines to be dropped closer to the ground and connected to apparatus for disconnecting, protecting, and stepping down the voltage, e.g., a switch, a circuit breaker and a transformer, respectively. Disconnect switches are located on or near the dead end frame structure between the transmission power lines and the power lines that are dropped to ground level (also known as xe2x80x9ctap connectionsxe2x80x9d). The switches can be used to cut off power to the substation and physically isolate the electrical connection between the substation and the transmission line.
Three main types of dead end frame structures have conventionally been used to anchor both transmission and distribution lines. An xe2x80x9cAxe2x80x9d frame structure has been used as a deadend structure and includes four beams that rise in pairs from the ground and angle towards each other to meet at two spaced apart connection points. Horizontally oriented beam(s) bridge the two pairs of beams to create the xe2x80x9cAxe2x80x9d frame structure. Transmission lines are connected to and terminate at the horizontally oriented beam(s). The xe2x80x9cAxe2x80x9d frame has four legs and therefore requires a large foundation for connection of each of its legs to the ground. Thus, the xe2x80x9cAxe2x80x9d frame also requires a large amount of ground area due to the relatively large xe2x80x9cfootprintxe2x80x9d of the connective foundation.
An xe2x80x9cHxe2x80x9d frame structure has also been conventionally used as a deadend structure. The xe2x80x9cHxe2x80x9d frame structure has two beams that extend from the ground and are joined at their mid-section by a cross beam. Transmission lines are connected to and terminate at the cross beam. The xe2x80x9cHxe2x80x9d frame also requires a large footprint to attach each of its two legs to the ground.
The third conventional dead end structure is a xe2x80x9cboxxe2x80x9d or xe2x80x9copenxe2x80x9d frame structure. The xe2x80x9cboxxe2x80x9d or xe2x80x9copenxe2x80x9d frame structure includes a plurality of leg members that are secured to foundations in the ground, with a box shaped structure including beams that are suspended by the legs. Transmission lines are connected to and terminate at the beams of the box shaped structure. Again, the many leg members result in a large footprint for the xe2x80x9cboxxe2x80x9d or xe2x80x9copenxe2x80x9d frame structure.
Conventional dead end structures require a large amount of real estate for installation due to their large footprints. The structures are also relatively expensive to manufacture due to the many different components and the cost of real estate, and are also difficult and timely to install. In addition, it is difficult to access remote and mountainous area with the conventional deadend structures due to their large footprint and relative difficult and time consuming installation process.
The invention is directed to a structure and method that xe2x80x9canchorsxe2x80x9d the ends of a transmission line at a substation or other location and uses a minimal amount of area for ground connection, i.e., leaves a small footprint. The invention includes a single pole on which each of the ends of a 3 phase transmission line can be connected and by which the transmission line can be dropped from the top of the single pole to an electrical apparatus on the ground level. The pole can be physically connected to the ground via a single foundation in order to use the least amount of area for installation.
Additional features and advantages of the invention will be set forth in the description that follows, and in part, will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and achieved by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve this and other advantages, and in accordance with the purpose of the invention as embodied and broadly described, the invention provides a single pole utility line deadend structure that includes first, second and third connectors positioned on the single pole at first, second and third connector locations, respectively. The connectors can be configured in a vertical row for connection to transmission lines. A fourth connector is preferably positioned on the single pole at a fourth connector location that is at a different elevation and a different circumferential position than said first, second and third connector locations with respect to said single pole.
In accordance with another aspect of the invention, a single pole includes means for connecting to transmission lines and means for dropping three phase power lines from a first elevation to a second lower elevation along said single pole.
In accordance with yet another aspect of the invention, a method for dropping electric wire to a lower level includes providing a single pole structure and connecting a first wire at a first location on the single pole. The method includes connecting a first wire at a second location that is at a different elevation and different circumferential position with respect to the single pole structure than the first location. The method also includes dropping the first wire along the single pole structure from the second location.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.